Retractable keel for sailboats



Sept. 25, 1951 RETRACTABLE KEEL FOR SAILBOATS L. G. WILSON Filed Jan. 15, 1947 (Ittomegs ticular to keels therefor.

Patented Sept. 25, 1951 UNITED STATES PATENT OFFICE RETRACTABLE KEEL FOR SAILBOATS Loudon G. Wilson, Fairhaven, Mich.

Application January 15, 1947, Serial No. 722,234

I I 1, l This invention relates to sailboats and in par- One object of this invention is to provide a retractable keel for sailboats which is foldable up against the bottom of the boat so as to permit the boat to sail in shallow water or over underwater obstructions.

Another object is to provide a retractable keel for sailboats wherein the keel remains entirely outside the boat either in its extended or retracted position, thereby completely eliminating the trunk or box ordinarily used with conventional centerboards and accordingly providing a loweringthe keel also serves as a stiffening mem-' 'ber to provide additional rigidity to the keel against the side stresses applied thereto while sailing into the wind or on a broad reach.

Another object is to provide a retractable keel for sailboats, as set forth inthe preceding objects, wherein the keel is composed of a plurality of approximately triangular relatively narrow plates which are hinged to one another along their long edges and are hinged in a fore and aft direction to the keel, a pair of such assemblies being mounted side by side and folded upward in opposite directions against the bottom of the boat.

Another object is to provide a retractable keel for sailboats as set forth in the preceding objects, wherein the keel in its partially retracted position is of diamond-shaped cross-section and forms a hollow horizontal pyramid so that the partially retracted keel acts as a sea anchor when the boat is headed into the wind.

Another object isto provide a retractable keel for sailboats, asset forth in the preceding objects, wherein the complete absence of the conventional centerboard trunk eliminates the leaks constantly occurring around such trunks, as well as the weakening of the hull brought about by the inclusion of the centerboard trunk.

Other objects and advantages of the invention will become apparent during the course of the following description of the accompanying drawings, wherein:

Figure 1 is a side elevation of a sailboat with a retractable keel according to a preferred form of the invention, with the keel in its extended position;

6 Claims. (Cl. 114133) Figure 2 is a substantially verticalcross-section taken along the line 22 in Figure 1, showing the keel in its extended position and partially retracted in dotted lines;

Figure 3 is a cross-section similar to Figure 2,

but with the keel in its fully retracted position;

and l Figure 4 is an enlarged fragmentary. side elevation of the lower central portion of Figure 1, partly broken away to show the connection of the operating rod to the keel.

Referringto the drawings in detail, Figure 1 shows a sailboat, generally designated HI, equipped with a retractable keel, generally designated I I, according to a preferred form of the invention. The sailboat II has a hull generally designated [2, of any suitable design, whether round-bottom, V-bottom or flat bottom style. A V-bottom hull is shown for purposes of illustration, but not by way of limitation, as it is readily apparent that the retractable keel l I may be employed in substantially any type of hull.

1 The hull 12 includes the usual bottom planking 13, side planking l4, rubbing strakes l5, stem l6, fixed keel l1, skeg l8 and stern planking l9. Se" cured to the keel l1 forward of the retractable keel II is a nose piece or fairing piece 20 which serves to present the forward edge of the folding keel ll smoothly to the water. Also secured as at 2| to the bottom planking l3 (Figure 2) of the hull I2 immediately abaft the nose piece 20 and adjacent the downwardly-projecting external portion of the fixed keel I! on each side thereof is a pair of elongated angle plates 22.

Each of the lower edges of the angle plates 22 terminates in the hinge connection 23 with the upper edge of an upper folding keel plate 24 which, in turn, is provided with a hinge connection 25 along its lower edge to a lower folding hinge plate 26. In the extended position of the retractable keel I I (Figure 2), the two upper keel plates 24 are substantially parallel whereas the lower keel plates 26 converge toward one another to a common hinge connection 21 having a hinge rod 28 running upward longitudinally toward the nose piece 20. The keel plates 24 and 26 are roughly triangular and may be constructed of metal or wood, as desired, and may be stiffened as found necessary.

In order to raise and lower the retractable keel ii, an operating rod or shaft 29 is provided and may be either solid or tubular. The lower portion of the operating rod 29 passes between the upper and lower keel plates 24 and 26 and is provided with a hole 30 for the hinge rod 28, which terminates in a head 3| adjacent the cutaway portions 32 of the keel plates 26.

The upper portion of the operating rod 29 passes through a, tubular well 33 which extends upward through a hole 34in the keel I! (Figing l4.

ving of the-operating rod 29.

ure 2) and is braced fore and aft by roughly triangular knees or brace blocks 35 and 36 (Figure 1). To provide a seat upon which an oarsmanmay .sittorow theboat whenbecalmed, a thwart 31 is mounted. between the side plank- The thwart 3'! may be omitted if desired, as it is not needed for bracing. The keel plates 24, 26 when lowered are virtually selfbracing since their converging arrangement forms a triangular structure from their spaced upper connections 23 to their common lower connection 28. The upper .end of the tubular well 30 passes through a hole 38 in the thwart 31 and is provided with a pair of transverse aligned holes 39 for receiving a pin 40 which "may be-passed through one of several transverse -holes H in the operating rod 29 in such a. mannerthat-the latter may be firmly held in any one of several difierent positions. The lowermost hole 'fll is so located (Figure 3) as to come in line'withthewell hole-39 when the retractable keel II is in its fully retracted position.

Thenpper end of the operating rod or shaft 29 is provided with an upwardly-projecting portion or car 42 through "which-a ring d? passes. The ring 43 facilitates the raising'and lower- For simplicity of showing the operating rod 29 is illustrated as being in a single-piece. In actual practice, however, it is convenient 'toprovide a knuckle joint (not. shown) immediately above the lowermost hole' ll 'topermit the upper portion of the operating rodZS 'to be folded'down when theretractable keel II is fully retracted (Figure 3), thus reducing possible interference with the "boom, ,mainsheet orother portions of the boat or its. rigging. ;The lower portion of the operating rod 29,. .if tubular, is provided with drainage iholes M for permitting water to drain out of .the interior when the rod isiraised.

Operation Inthe operation of the invention, in navigating through shoal water, the retractable keel II is raised to its fully retracted position (Figure 3) by hauling the operating-rod 29 upward, the pin 40 being then inserted through the holes 39 in the well 33 and the lowermost hole 4| in the operating rod 29. As the rod 29 is hauled upward, the hinge connections 25 break in an outward direction and the lower and upper keel plates 24 move outward and upward through the dotted line position shown in Figure 2 to the solid line position shown in Figure 3. In the retracted position of Figure 3, the draft of the boat is at its minimum, permitting the boat to pass over obstructions or through shallow water, over sand bars or to land upon a beach.

In sailing into the wind or on the Wind, the

retractable keel H is lowered to its lowermost position shown in solid lines in Figure 2. This is done by withdrawing the pin 40 from the lowermost hole fill, pushing the operating rod 29 downward to its full extent and reinserting the pin 40 in the uppermost hole Al, the pin, of

course, in both instances, passing through the holes39 in the tubular well 33. When the operating rod 29 is pushed downward, to its fullest extent, the upper keel plates 24 move into substantially parallel positions and the hinge conponent of the force exerted by the wind upon the sail and transmitted to the hull through the mast and standing and running rigging. If the boat. is sp.-rigged,.the ...force exerted by the wind upon the jib adds to the athwartships component, thus adding further thrust to the keel plates 24 and 26, which is in part sustained by the operating rod 29.

In heaving to, as for making or furling sail, tying in a reef or the like, the bow of the boat is, of course, headed into the wind. With the boat thus hove to, it is found convenient to raise the retractable keel to an intermediate position, such as is shown in chain lines in Figure 2. When the keel II is in this position, it forms a hollowrpyramid with the-apex adjacent the nose or fairing piece 20 and -the'open base aft. The

:shape is thus approximately that of a sea anchor and the keel so :acts, to impede the sternway -:otherwise imparted to the boat by the force of ttic-wind. the retractable keel in its intermediate position is of great assistance to the 'sailor in reducing the danger of accidentally small tubular well '33 and its braces 25,36 and "31.

By thus providing more room within the cockpit, a cabin or cubby may be incorporated in the design of a boat where such would-beimpractical in a centerboard type of boatydue to the obstruction presented by the centerboard trunk extending upward in the 'm-iddle of the --cabin. At the same time, the disadvantages of the deep fixed keel are avoidedwhile its advantages-as affecting the'freedom of obstruction within the 'boat are preserved.

What I claim is:

l. A retractable keel construction for a sailboat comprising a supporting fixture adapted'to "be-"secured to the boat a pair of upper keel plates hinged to said fixture, apair of lower keel plates hinged to said upper keel plates and hingedly interconnected to each other, the pivotal axes of said hinges converging upwardand forward, and a movable operating membercon- -nected to one-of said-keel-plates-for folding said keelpla-tes outward and upward.

2. A retractable keel construction for'a sailboat comprising a supporting fixture adaptedto be secured to the boat, a pair of upper keel plates hingedto said fixture, a pair of lower keel plates hinged to saidupper keel plates and hingedly interconnected to each other, and a movable operating member connected to the lower hinge connection of saidlower keel plates and extending upward bet-ween both pairs of said keel plates, said member being operable to stiffen said :keel plates in their lowered positions and also to raise them and hold them .outwardan'd upward.

3. Aretractable keel construction for-a sailboat comprising a supporting fixture adapted to be secured to the boat, a pair of upper :keel plates hinged to said fixture, a pair of lower keel plates hinged to .said upper kee1 plates and hingedly interconnected to each other, a water excluding device adapted to extend upward through the bottom of the boat, and a reciprocable operating member mounted in said device, said operating member being connected to the lowermost pair of said keel plates and extending upward between both pairs of said keel plates, said member being operable to stiifen said keel plates in their lowered positions and also to raise them and hold them outward and upward.

4. A retractable keel construction for a sailboat comprising a supporting fixture adapted to be secured to the boat and having two sets of laterally spaced pivots, a pair of upper keel plates pivoted one to each set of pivots, a pair of lower keel plates, a hinge structure pivotally connecting each lower keel plate to one of said upper keel plates, another hinge structure pivotally interconnecting the lower portions of said lower keel plates, the pivotal axes of said hinge structures converging upward and forward and a movable operating member operatively connected to one of said keel plates and operable to fold said keel plates outward and upward, one pair of said keel plates being of approximately triangular outline.

5. A retractable keel construction for a sailboat comprising a supporting fixture adapted to be secured to the boat and having two sets of laterally spaced pivots, a pair of upper keel plates pivoted one to each set of pivots, a pair of lower keel plates pivoted one to each upper keel plate, a connecting structure pivotally interconnecting the lower portions of said lower keel plates, and a movable operating member operatively connected to one of said keel plates and operable to fold said keel plates outward and upward, both 85 172,591

pairs of said keel plates being of approximately triangular outline.

6. A retractable keel construction for a sailboat comprising a supporting fixture adapted to be secured to the boat and having two sets of laterally spaced pivots, a pair of upper keel plates pivoted one to each set of pivots, a pair of lower keel plates, a hinge structure pivotally connecting each lower keel plate to one of said upper keel plates, another hinge structure pivotally interconnecting the lower portions of said lower keel plates, the pivotal axes of said hinge structures converging upward and forward and a movable operating member operatively connected to one of the lowermost of said keel plates and extending upward between both pairs of keel plates, said member being operable to stifien said keel plates in their lowered positions and also to raise them and fold them outward and upward.

LOUDON G. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 76,896 Dirkes Apr. 21, 1868 93,070 Dillon July 27, 1869 258,375 Clapham May 23, 1882 FOREIGN PATENTS Number Country Date m ny un 3, 1906 

